#pragma warning(disable : 4996)
#include"snake.h"

//int main()
//{
//	srand((unsigned)time(NULL));
//	Snake snake;
//	snake.Run();
//
//	
//}

#include<stdio.h>
int main()
{
	int n = 0;
	scanf("%d", &n);
	int totalcout = 0;
	for (int i = 1; i <= n; i++)
	{
		int count = 0;
		for (int j = 1; j <= i; j++)
		{
			count += j;
		}
		totalcout += count;
	}
	printf("%d\n", totalcout);
}